A global record of particulated metals on the southwestern Atlantic shelf (Argentine Sea)

Abstract

The Argentine Sea (Southwestern Atlantic) is one of the most productive ecosystem in the Southern Hemisphere. Research on metals in this region is scarce or null. In this study, we evaluated the concentrations of some metals in the suspended particulate matter (SPM), to provide baseline data that would enable us to understand the role of the SPM in the transport of metals in the Argentine Sea. Sampling was carried out during the austral summer 2016 at 20 stations distributed in the Argentine Sea. Surface seawater samples were collected and then filtered by vacuum through Millipore® HAWP 04,700 filters (0.45 µm). The samples were acid-digested (HNO3 and HClO4, 5:1) and the metal concentrations were determined with ICP-OES Optima 2100 DV (Perkin Elmer). Significant spatial variations were detected due to the extension of the study area, with the highest levels of metals in the stations next to large urban centers (Cd, Cu, Cr, Fe, Mn, Ni, Pb and Zn: 13.9, 154.9, 48.7, 54,470, 7646, 49.2, 58.6 and 509.5 μg g−1 d.w. respectively), which was supported by the nMDS and Cluster analyses. According to PCA analysis, two groups of metals that could have similar behavior were stablished: one group integrated by Cu, Zn, Pb and Ni, and the other group integrated by Cr, Fe and Mn. Metals that act as micronutrients and the toxic ones were present in all the sampling stations, highlighting the need to reinforce the study of these elements in this extensive and productive area of the South Atlantic Ocean.